MacOS – Why might more memory be wired in safe mode than in normal mode

macosmemorysafe-mode

Maybe more noticeable in Lion and Mountain Lion, than in Snow Leopard and earlier versions of the operating system:

in safe mode, an unexpectedly large amount of wired memory.

Question

Why might more memory be wired in safe mode?

Example

Screenshots of Mountain Lion in safe and normal modes on a MacBookPro5,2 with 8 GB memory:

with a safe boot, more than 5 GB is wired after login
with a normal boot, less than 2 GB.

Links

Mac OS X: What is Safe Boot, Safe Mode?

What is wired memory?

Mac virtual memory: how to make OS X create swap (page) files as freely with a normal boot as it does with a safe boot (swapfile1 etc)

XNU questions in Stack Overflow

Best Answer

SafeBoot disables various kernel extensions including the GPU. The extra memory is likely being used for the display where it would normally be allocated to share with integrated graphics or be handled by a discreet graphics card.

Related Solutions

MacOS – How to resolve error: “Couldn’t modify partition map because file system verification failed”

OK, this isn't too bad. Reboot while holding Command ⌘-S to enter single user mode. When it gives you a prompt, type

fsck -fy

then press return. it will repair your disk. When it's done, type

reboot

and try partitioning again.

MacOS – What version of GDB version is included in your Xcode

The version on my system (Mountain Lion, XCode 4.5 is:

GNU gdb 6.3.50-20050815 (Apple version gdb-1822) (Sun Aug  5 03:00:42 UTC 2012)

Basically, 6.3 is the last version covered by the GPLv2 license, everything past that is subject to GPLv3. Apple does not distribute any GPLv3 software, presumably as it would seriously hinder their patent lawsuits. (this is also why OSX or XCode no longer ship with Samba or GCC newer than 4.2)

By the way, the last version of XCode for Snow Leopard is 4.2, but as far as I know this is only available in the downloads section to iOS or Mac developer program subscribers.